The carrier is sort of free floating Ted, the retainer is what keeps it in place, if the retainer is loose so is the carrier. Iirc when the retainer is fitted correctly there is a very small gap of around 0.5-1.0mm between the flange of the retainer and the carrier. It cannot be locked tight as under acceleration the carrier compresses the damper rubbers and twists forward, hence why it needs to be greased between the hub and the carrier bush, it’s why the grooves are there to retain grease. Seen quite a few where the grease has either dried out or the bearing was fitted dry that wore the bushing in the carrier oval.